Haines Borough Fish Passage Inventory and Assessment
All fresh-water fish need to move freely up and down the streams and rivers they inhabit to take advantage of food sources, find places to lay eggs, or escape predators and unfavorable conditions. Barriers in the stream damage fish populations simply by blocking access to habitat. The ability to move along a stream is especially crucial to anadromous fish. Remember that the fish must swim upstream, against the flow of water, in some cases leaping up waterfalls, but in all cases fighting against the current. Anadromous fish race against time to find mates and nest sites before they, quite literally, run out of fuel and die. Any barrier to their upstream journey wastes valuable time and energy. Fish Passage is the term that refers to a fish’s ability or inability to move through barriers, such as culverts, fish ladders, natural waterfalls, and areas of especially high or low water. Fisheries biologists, sportfishing groups, and local watershed councils in our area work towards making sure that passage is easy for all sizes and species of our finned friends.
Probably the most problematic barriers are the culverts which are placed where streams and roads intersect. Culverts that are too small or too steeply angled result in water velocities that the fish cannot overcome. “Perched” culverts are set too high above the stream level, and present insurmountable barriers, effectively rendering the upstream habitat unusable to migrating fish. The State of Alaska is unique among the 50 states in the legal protection it gives to fish passage- a wise move by a state whose residents rely so much on from the harvest of healthy salmon populations. Obstructions such as dams must allow effective fish passage, and culverts must be of proper size, gradient, and material to allow fish to complete their upstream trek. Undersized culverts are generally easy to replace when they are identified as blocking fish passage.
TWC started an assessment of all road crossings in listed anadromous habitat in 2008. Data was taken at each crossing to determine the ability of a culvert to pass juvenile fish upstream. These data have informed a short-list of potential culvert replacement projects that the council will investigate further.